Worksheet 11: DNA Structure & Replication Biology Directions: Answer in complete sentences. 1. What are nucleotides? 2. What are the three parts of each nucleotide? 3. What are the four different nucleotides? 4. Which nucleotides have single ring structure? 5. Which nucleotides have double ring structure? 6. How do A and T pair together? What about G and C? 7. What is DNA replication? 8. What is the first step in the replication process? 9. What happens once the 2 strands of DNA are unzipped? 10. What two things do the DNA polymerases do?